The disclosure relates generally to fiber optic cables, and more particularly to fiber optic assemblies including a furcation body, fan-out assemblies used in such fiber optic assemblies, and methods of furcating fiber optic cables to form such fiber optic assemblies.
Fiber optic cables are widely used in the telecommunications industry to transmit voice, video, and data signals. The cables include one or more optical fibers surrounded by one or more layers of material designed to protect the optical fibers from the environment in which the cables are used. To meet ever-increasing bandwidth demands, fiber optic cables are being developed with relatively large numbers of optical fibers. These high fiber count cables are often the trunk cables that form the backbone of transmissions in local area networks (LANs) and data centers.
In many instances, the optical fibers in a high fiber count cable are arranged ribbons each containing multiple rows optical fibers (e.g., 12 optical fibers per ribbon). The ribbons are stacked on top of each other and may be arranged in arrays with more than one row of stacked ribbons. Ribbon cables provide the highest fiber density relative to cable diameter, allowing the most efficient use of pathways and spaces where the cables must be routed. For these and other reasons, ribbon cables are the primary choice of cable type for applications where fiber counts of 24 or more are required.
One of the challenges associated with using high fiber count cables is that ultimately the cables must be terminated to allow mating with equipment or other fiber optic cables. Termination typically involves installing fiber optic connectors onto the optical fibers. For example, ribbons may be split into individual optical fibers to allow simplex connectors (e.g., LC or SC connectors) to be installed on respective optical fibers or duplex connectors to be installed on respective pairs of optical fibers. Alternatively, multi-fiber connectors (e.g., MTP connectors) may be installed onto each ribbon. Harnesses or modules may then be used to breakout the multi-fiber connectors into simplex or duplex connectors.
Termination can be done in the field, but factory-terminated cables are typically desired for high fiber count trunks because such preterminated cable assemblies expedite installations and are generally associated with lower connector insertion losses. One way of providing a preterminated cable assembly involves using a furcation to distribute/separate the optical fibers from a trunk cable. The furcation includes a body or plug formed over a portion of the cable where the protective layers have been removed to expose the optical fibers. The body or plug is also formed over a portion of furcation tubes/legs that are placed over the exposed optical fibers. The furcation legs provide protection between the furcation body or plug and the connectors. With such an arrangement, the furcation body terminates the strength members and helps isolate fiber strain in the cable from the connectors. The furcation is also able to serve as a load distribution point for pulling grips and as an attachment point to attach the cable assembly to racks, cabinets, or other hardware.
As fiber counts increase, furcating trunk cables becomes more difficult. Guiding the optical fibers into furcation legs can be difficult to manage, especially when attempting to minimize the size of the furcation. Size is an important consideration because if the furcation is too large, the cable assembly may be too big to be pulled through existing ducts and other pathways and/or may limit bend radius to unacceptable values. Space constraints, budgets, installation times, and other practical considerations may not allow for providing larger ducts/pathways.